The histopathological features of four cases of placental involvement in schistosomiasis mansoni are described. One of the pregnancies resulted in a normal newborn, the other three in stillbirths. Adult worms were found in the intervillous space in one case and in the decidual vessels in another. Eggs were found in the placenta in all cases, in the intervillous space, within villi, or in the decidua. There was no evidence of fetal infection. The differential diagnosis with other forms of granulomatous placentitis is discussed.